Regional specialization within the intestinal immune system. Nat Rev Immunol. 2014;14:667-685. [PMID: 25234148 DOI: 10.1038/nri3738]

Bifidobacterium longum subsp. longum XZ01 delays the progression of colon cancer in mice through the interaction between the microbial spatial distribution and tumour immunity

Studies have shown that the colonisation of active microorganisms is more conducive to the development of tumour immunotherapy, but intuitive evidence regarding shaping of the tumour immune microenvironment is lacking. In this study, we used Bifidobacterium longum subsp. longum (XZ01) to intervene in a colon cancer mouse model and found that its mechanism may be related to the interaction between the spatial distribution of microorganisms and tumour immunity. Through the visualisation method we established, for the first time, we showed that harmful active bacteria such as Streptococcus and Rhodococcus specifically accumulate in the middle and upper layers of tumour tissue. These bacteria likely participate in signalling pathways that affect macrophages by directly contacting or invading the macrophages, leading to a nondifferentiated state in macrophages and the loss of some immune functions. Furthermore, the accumulation of Streptococcus and Rhodococcus fragments in the deep layer of tumour tissue likely upregulates the expression of IL-10 in tumour tissue and inhibits other immune cells, such as CD8+ T cells, DC and NK cells. In contrast, XZ01 can specifically compete for the growth sites of Streptococcus and Rhodococcus in the middle and upper layers of tumour tissue and probably protects macrophages from being invaded by harmful bacteria. XZ01 directly regulates the polarisation of M0 macrophages towards the M1 phenotype by upregulating IFN-γ, thus activating tumour immunity to inhibit the growth of tumour cells. This study revealed that the influence of active microorganisms on the tumour immune microenvironment is crucial for effective immunotherapy intervention, potentially offering new targets for improving patient prognosis.

CXCR3 inhibition ameliorates mitochondrial function to mitigate oxidative damage through NCOA4-mediated ferritinophagy and improves the gut microbiota in mice

Nuclear receptor coactivator 4 (NCOA4)-mediated ferritinophagy contributes to maintain intracellular iron balance by regulating ferritin degradation, which is essential for redox homeostasis. CXC-motif chemokine receptor 3 (CXCR3) is involved in the regulation of oxidative stress and autophagy. However, its role in modulating intestinal oxidative damage through ferritinophagy and the gut microbiota remains unclear. In this study, the impacts of CXCR3 inhibition on intestine oxidative damage, ferritinophagy, and the gut microbiota, as well as the mitochondrial quality control were investigated both in vivo and in vitro. The results show that CXCR3 inhibition by AMG487 relieves Diquat-induced intestinal damage, enhances the expression of tight junction proteins, and promotes antioxidant capacity in mice. Simultaneously, CXCR3 inhibition improves gut microbiota composition, and triggers NCOA4-mediated ferritinophagy. Mechanistically, the effects of CXCR3 inhibition on ferritinophagy were explored in IPEC-J2 cells. Co-localization and interaction between CXCR3 and NCOA4 were observed. Downregulation of NCOA4-mediated ferritinophagy leads to increase the expression of tight junction proteins, reduces iron levels, restricts ROS accumulation, and enhances GPX4 expression. Moreover, CXCR3 suppression facilitates mitochondrial biogenesis and mitochondrial fusion, increases antioxidative capacity, and results in the elevation of tight junction proteins expression. These findings suggest that CXCR3 inhibition reverses Diquat-induced intestinal oxidative damage, enhances mitochondrial function, and improves gut microbiota composition by elevating NCOA4-mediated ferritinophagy, which implies that CXCR3 may serve as a potential therapeutic intervention targeting iron metabolism for treating intestinal diseases.

Zinc Deficiency Reduces Intestinal Secretory Immunoglobulin A and Induces Inflammatory Responses via the Gut-Liver Axis

Nutritional zinc (Zn) deficiency could impair immune function and affect bowel conditions. However, the mechanism by which Zn deficiency affects the immune function of gut-associated lymphoid tissue (GALT) remains unclear. We investigated how Zn deficiency affects the function of GALT and level of secretory IgA (sIgA), a key component of the intestinal immune barrier, its underlying mechanisms, and whether Zn deficiency induces bacterial translocation to the liver. As previous research has indicated that interleukin (IL)-4 administration or Zn supplementation has a beneficial effect on the spleen of Zn-deficient rats, we investigated whether these supplements reverse the GALT immune system. Five-week-old male rats were fed a standard diet, Zn-deficient diet supplemented with saline or IL-4 for 6 weeks, or Zn-deficient diet followed by a standard diet for 4 weeks. Zn deficiency suppressed sIgA secretion in the intestinal tract by affecting GALT function and induced inflammatory responses through bacterial translocation to the liver via the portal vein. Furthermore, IL-4 administration and Zn supplementation in rats with Zn deficiency elicited comparable beneficial effects on GALT function, suggesting that the administration of either IL-4 or Zn could prevent inflammatory response via bacterial translocation to the liver.

PGLYRP1-mediated intracellular peptidoglycan detection promotes intestinal mucosal protection

Peptidoglycan recognition proteins (PGLYRPs) are implicated in the control of the intestinal microbiota; however, molecular requirements for peptidoglycan (PGN) binding and receptor signaling mechanisms remain poorly understood. Here we show that PGLYRP1 is a receptor for the disaccharide motif of lysine N-acetylglucosamine N-acetylmuramic tripeptide (GMTriP-K). PGLYRP1 is required for innate immune activation by GMTriP-K but not muramyl dipeptide (MDP). In macrophages, intracellular PGLYRP1 complexes with NOD2 and GEF-H1, both of which are required for GMTriP-K-regulated gene expression. PGLYRP1 localizes to the endoplasmic reticulum and interacts at the Golgi with NOD2 upon GMTriP-K stimulation. PGLYRP1 and dependent gene expression signatures are induced in both mouse intestinal inflammation and human ulcerative colitis. Importantly, PGLYRP1 activation by GMTriP-K can result in the protection of mice from TNBS-induced colitis. Mammalian PGLYRPs can function as intracellular pattern recognition receptors for the control of host defense responses in the intestine.

Bi-directional communication between intrinsic enteric neurons and ILC2s inhibits host defense against helminth infection

Emerging studies reveal that neurotransmitters and neuropeptides play critical roles in regulating anti-helminth immune responses, hinting at the potential of intrinsic enteric neurons (iENs) in orchestrating intestinal immunity. Whether and how iENs are activated during infection and the potential neuroimmune interactions involved remain poorly defined. Here, we found that helminth infection activated a subset of iENs. Single-nucleus RNA sequencing (snRNA-seq) of iENs revealed alterations in the transcriptional profile of interleukin (IL)-13R+ intrinsic primary afferent neurons (IPANs), including the upregulation of the neuropeptide β-calcitonin gene-related peptide (CGRP). Using genetic mouse models and engineered viral tools, we demonstrated that group 2 innate lymphoid cell (ILC2)-derived IL-13 was required to activate iENs via the IL-13R, leading to iEN production of β-CGRP, which subsequently inhibited ILC2 responses and anti-helminth immunity. Together, these results reveal a previously unrecognized bi-directional neuroimmune crosstalk in the intestine between a subset of iENs and ILC2s, which influences pathogen clearance.

CD3γ/δ+ T cells and MSCFR+ macrophages are activated to produce IL-26 after bacterial infection in grass carp

Interleukin-26 (IL-26) belongs to the IL-10 cytokine family and exerts diverse biological functions in regulating immune responses in vertebrates. Although IL-26 has been extensively studied in mammals, the functions of IL-26 remain largely unexplored in lower vertebrates. In this study, we determined the tissue and cell sources of IL-26 using a monoclonal antibody (mAb) generated against grass carp (Ctenopharyngodon idella, Ci) IL-26, and investigated the responses of IL-26 producing cells to bacterial infection. We showed that the CiIL-26 mAb specifically recognized the recombinant CiIL-26 proteins expressed in the Escherichia coli and HEK293 cells. Flow cytometry analysis revealed that the CiIL-26 mAb could detect the intracellular CiIL-26 expressed in the HEK293 cells and CIK cells stimulated with inactivated Aeromonas hydrophila (A. hydrophila). Using confocal microscopy, we analyzed IL-26+ cells in various tissues of grass carp following infection with A. hydrophila. It was shown that the IL-26+ cells were significantly increased in the gills, head kidney, posterior intestine and spleen. Remarkably, for the first time, we observed that most IL-26+ cells were CD3γ/δ+ T cells and MCSFR+ monocytes/macrophages, which could be induced by A. hydrophila. Our findings highlight the essential roles of CD3γ/δ+/IL-26+ T cells and MCSFR+/IL-26+ macrophages in the immune defense against bacterial infections in fish.

Serotonin attenuates tumor necrosis factor-induced intestinal inflammation by interacting with human mucosal tissue

The intestine hosts the largest immune system and peripheral nervous system in the human body. The gut‒brain axis orchestrates communication between the central and enteric nervous systems, playing a pivotal role in regulating overall body function and intestinal homeostasis. Here, using a human three-dimensional in vitro culture model, we investigated the effects of serotonin, a neuromodulator produced in the gut, on immune cell and intestinal tissue interactions. Serotonin attenuated the tumor necrosis factor-induced proinflammatory response, mostly by affecting the expression of chemokines. Serotonin affected the phenotype and distribution of tissue-migrating monocytes, without direct contact with the cells, by remodeling the intestinal tissue. Collectively, our results show that serotonin plays a crucial role in communication among gut-brain axis components and regulates monocyte migration and plasticity, thereby contributing to gut homeostasis and the progression of inflammation. In vivo studies focused on the role of neuromodulators in gut inflammation have shown controversial results, highlighting the importance of human experimental models. Moreover, our results emphasize the importance of human health research in human cell-based models and suggest that the serotonin signaling pathway is a new therapeutic target for inflammatory bowel disease.

IgA facilitates the persistence of the mucosal pathogen Helicobacter pylori

IgA antibodies have an important role in clearing mucosal pathogens. In this study, we have examined the contribution of IgA to the immune control of the gastrointestinal bacterial pathogens Helicobacter pylori and Citrobacter rodentium. Both bacteria trigger a strong local IgA response that results in bacterial IgA coating in mice and in gastritis patients. Class switching to IgA depends on Peyer's patches, T-cells, eosinophils, and eosinophil-derived TGF-β in both models. In the case of H. pylori, IgA secretion and bacterial coating also depend on a functional bacterial type IV secretion system, which drives the generation of Th17 cells and the IL-17-dependent expression of the polymeric immunoglobulin receptor PIGR. IgA-/- mice are hypercolonized with C. rodentium in all examined tissues, suffer from more severe weight loss and develop more colitis. In contrast, H. pylori is controlled more efficiently in IgA-/- mice than their WT counterparts. The effects of IgA deficiency of the offspring can be compensated by maternal IgA delivered by WT foster mothers. We attribute the improved immune control observed in IgA-/- mice to IgA-mediated protection from complement killing, as H. pylori colonization is restored to wild type levels in a composite strain lacking both IgA and the central complement component C3. IgA antibodies can thus have protective or detrimental activities depending on the infectious agent.

Transport functions of intestinal lymphatic vessels

Lymphatic vessels are crucial for fluid absorption and the transport of peripheral immune cells to lymph nodes. However, in the small intestine, the lymphatic fluid is rich in diet-derived lipids incorporated into chylomicrons and gut-specific immune cells. Thus, intestinal lymphatic vessels have evolved to handle these unique cargoes and are critical for systemic dietary lipid delivery and metabolism. This Review covers mechanisms of lipid absorption from epithelial cells to the lymphatics as well as unique features of the gut microenvironment that affect these functions. Moreover, we discuss details of the intestinal lymphatics in gut immune cell trafficking and insights into the role of inter-organ communication. Lastly, we highlight the particularities of fat absorption that can be harnessed for efficient lipid-soluble drug distribution for novel therapies, including the ability of chylomicron-associated drugs to bypass first-pass liver metabolism for systemic delivery. In all, this Review will help to promote an understanding of intestinal lymphatic-systemic interactions to guide future research directions.

Organismal mucosal immunology: A perspective through the eyes of game theory

In complex organisms, functional units must interact cohesively to maintain homeostasis, especially within mucosal barriers that house diverse, specialized cell exposed to constant environmental challenges. Understanding how homeostasis at mucosal barriers is maintained and how its disruption can lead to autoimmune diseases or cancer, requires a holistic view. Although omics approaches and systems immunology have become powerful tools, they are not without limitations; interpretations may reflect researchers' assumptions, even if other explanations exist. In this perspective, I propose that applying game theory concepts to mucosal immunology could help interpret complex data, offering fresh perspectives and supporting the exploration of alternative scenarios. By framing the mucosal immune system as a network of strategic interactions with multiple possible outcomes, game theory, which analyzes strategic interactions and decision-making processes, could illuminate novel cell types and functions, cell interactions, and responses to pathogens and commensals, leading to a more comprehensive understanding of immune homeostasis and diseases. In addition, game theory might encourage researchers to consider a broader range of possibilities, reduce the risk of myopic thinking, and ultimately enable a more refined and comprehensive understanding of the complexity of the immune system at mucosal barriers. This perspective aims to introduce game theory as a complementary framework for mucosal immunologists, encouraging them to incorporate these concepts into data interpretation and system modeling.

Segmental Regulation of Intestinal Motility by Colitis and the Adaptive Immune System in the Mouse Ileum and Colon

Gastrointestinal motility disturbances are a hallmark of inflammatory bowel disease (IBD); however, their mechanisms remain unclear. This study used a dextran sulfate sodium-induced colitis mouse model, deficient in mature B and T lymphocytes, to assess intestinal motility and the role of the adaptive immune system in health and IBD. In healthy mice, the absence of adaptive lymphocytes reduced acetylcholine (ACh) sensitivity in the ileum. During colitis, it decreases motility by reducing the intensity and frequency of spontaneous contractions while increasing cholinergic responsiveness. In the proximal colon, adaptive immunity deficiency led to increased contractility and reduced ACh sensitivity in homeostasis, whereas colitis reduced contractile capacity. In the mid colon, immune-deficient mice had reduced ACh sensitivity in homeostasis and exacerbated contractile responses during colitis. In the distal colon, adaptive immunity loss reduced contractility in health and cholinergic responsiveness during colitis. These motility alterations were associated with altered acetylcholinesterase and M2/M3 muscarinic receptor expression. Notably, adaptive lymphocyte deficiency resulted in reduced tissue damage and lower tumor necrosis factor-α expression in the colon during colitis, paralleling intestinal motility changes. Overall, the adaptive immune system critically regulates motility and inflammation across different intestinal segments in IBD.

Impact of Gut Microbiota on Lymphoma: New Frontiers in Cancer Research

The gut microbiome (GMB), which is made up of various microorganisms, plays a crucial role in maintaining the health of the host. Disruptions in this delicate ecosystem, known as microbial dysbiosis, have been linked to various diseases, including hematologic malignancies such as lymphoma. This review article explores the complex relationship between the GMB and the development of lymphoma and highlights its implications for diagnostic and therapeutic approaches. It discusses how GMB influences lymphoma development directly through the presence of certain microorganisms and indirectly through changes in the immune system. The clinical relevance of GMB is highlighted and its potential utility for diagnosis, predicting treatment outcomes and developing personalized therapeutic strategies for lymphoma patients is demonstrated. The review also looks at microbiome-targeted interventions such as fecal microbiome transplantation and dietary modification, which have shown promise for treating microbial dysbiosis and improving patient outcomes. In addition, it highlights the analytical challenges and the need for further research to fully elucidate the mechanistic functions of the GMB in the context of lymphoma. This review emphasizes the critical role of GMB in lymphomagenesis and its potential for the development of diagnostic and therapeutic strategies.

Mouse gut blueprint: regionality and resilience

Mayassi and colleagues utilized spatial transcriptomics to create a comprehensive blueprint of the mouse gut, exploring its adaptability and resilience under perturbed conditions. Their work highlights the adaptive capabilities of the murine gut's regionalized structure, providing insights into how it functions in a coordinated manner and how it responds to external challenges.

Application of Raman Spectroscopy in Non-Invasive Analysis of the Gut Microbiota and Its Impact on Gastrointestinal Health

The gut microbiota, a complex community of microorganisms, plays a crucial role in gastrointestinal (GI) health, influencing digestion, metabolism, immune function, and the gut-brain axis. Dysbiosis, or an imbalance in microbiota composition, is associated with GI disorders, including irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), and colorectal cancer (CRC). Conventional microbiota analysis methods, such as next-generation sequencing (NGS) and nuclear magnetic resonance (NMR), provide valuable insights but are often expensive, time-consuming, and destructive. Raman spectroscopy (RS) is a non-invasive, cost-effective, and highly sensitive alternative. This analytical technique relies on inelastic light scattering to generate molecular "fingerprints", enabling real-time, marker-free analysis of microbiota composition and metabolic activity. This review explores the principles, sample preparation techniques, and advancements in RS, including surface-enhanced Raman spectroscopy (SERS), for microbiota research. RS facilitates identifying microbial species, analysing key metabolites like short-chain fatty acids (SCFA), and monitoring microbiota responses to dietary and therapeutic interventions. The comparative analysis highlights RS's advantages over conventional techniques, such as the minimal sample preparation, real-time capabilities, and non-destructive nature. The integration of RS with machine learning enhances its diagnostic potential, enabling biomarker discovery and personalised treatment strategies for GI disorders. Challenges, including weak Raman signals and spectral complexity, are discussed alongside emerging solutions. As RS technology advances, mainly through portable spectrometers and AI integration, its clinical application in microbiota diagnostics and personalised medicine is poised to transform GI healthcare, bridging microbiota research with practical therapeutic strategies.

Inflammation-Induced Th17 Cells Synergize with the Inflammation-Trained Microbiota to Mediate Host Resiliency Against Intestinal Injury

BACKGROUND AND AIMS

Inflammation can generate pathogenic Th17 cells and cause an inflammatory dysbiosis. In the context of inflammatory bowel disease (IBD), these inflammatory Th17 cells and dysbiotic microbiota may perpetuate injury to intestinal epithelial cells. However, many models of IBD like T-cell transfer colitis and IL-10-/- mice rely on the absence of regulatory pathways, so it is difficult to tell if inflammation can also induce protective Th17 cells.

METHODS

We subjected C57BL6, RAG1-/-, or JH-/- mice to systemic or gastrointestinal (GI) Citrobacter rodentium (Cr). Mice were then subjected to 2.5% dextran sodium sulfate (DSS) to cause epithelial injury. Fecal microbiota transfer was performed by bedding transfer and co-housing. Flow cytometry, qPCR, and histology were used to assess mucosal and systemic immune responses, cytokines, and tissue inflammation. 16s sequencing was used to assess gut bacterial taxonomy.

RESULTS

Transient inflammation with GI but not systemic Cr was protective against subsequent intestinal injury. This was replicated with sequential DSS collectively indicating that transient inflammation provides tissue-specific protection. Inflammatory Th17 cells that have a tissue-resident memory (TRM) signature expanded in the intestine. Experiments with reconstituted RAG1-/-, JH-/- mice, and cell trafficking inhibitors showed that inflammation-induced Th17 cells were required for protection. Fecal microbiota transfer showed that the inflammation-trained microbiota was necessary for protection, likely by maintaining protective Th17 cells in situ.

CONCLUSION

Inflammation can generate protective Th17 cells that synergize with the inflammation-trained microbiota to provide host resiliency against subsequent injury, indicating that inflammation-induced Th17 TRM T cells are heterogenous and contain protective subsets.

Tetrahedral Framework Nucleic Acid Relieves Sepsis-Induced Intestinal Injury by Regulating M2 Macrophages

This study aimed to clarify the role and mechanism of tetrahedral framework nucleic acids (tFNAs) in regulating M2 macrophages to reduce intestinal injury. An intestinal injury model was established by intraperitoneal injection of lipopolysaccharides (LPS) in mice to explore the alleviating effects of tFNAs on intestinal injury. Inflammatory factors were detected by quantitative polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assay (ELISA). The intestinal barrier and permeability were assessed using western blotting and immunohistochemistry. Macrophages in the gut were localised and quantified using immunofluorescence. Western blotting was used to investigate the role and mechanism of tFNAs in regulating macrophages and alleviating inflammation in the injured intestines. These results show that tFNAs attenuated sepsis-induced intestinal injury. tFNAs can also promote the intestinal barrier reconstruction and reduce intestinal permeability. In vivo, tFNAs accelerated the aggregation of M2 macrophages at an early stage of injury and reduced the number of M1 macrophages in the intestine. In addition, tFNAs enhanced the clearance ability of intestinal macrophages. They activated the signalling and transcription activating factor 1(STAT1) and cytokine signalling inhibitory factor 1/3 (SOCS1/3) pathways by increasing the expression of the phagocytic receptor Mertk. These findings indicated that tFNAs can alleviate sepsis-induced intestinal injury by regulating M2 macrophages, providing a new option for treating intestinal injury.

Effect of high-fat diet on IgA+ cells and BAFF/APRIL in small intestinal villous lamina propria of mice

Obesity exacerbates susceptibility to infectious diseases. We investigated the effects of a high-fat diet (HFD) on intestinal immunity, particularly immunoglobulin (Ig)A-producing cells, B-cell activating factor (BAFF), and a proliferation-inducing ligand (APRIL) localization. Mice (4- to 20-weeks old) were fed HFD or standard chow diet, and their jejunum and ileum were fixed using the in vivo cryotechnique. Immunohistochemistry was performed for IgA, BAFF, and APRIL. In the HFD group, IgA+, IgA+CD22+ (p < 0.001), and IgA+CD138- (p = 0.007) cell counts were diminished in the middle sections of the lamina propria of jejunal villi, and BAFF levels were significantly reduced in jejunal villi. The HFD effects on IgA+ cell distribution seem to be confined to jejunal villi, hinting at localized vulnerabilities in intestinal immunity during obesity. Moreover, in the HFD group, IgA+ B-cell counts were reduced in the middle jejunum, indicating inhibition of the IgA+ B-cells through a T-cell-independent pathway.

Investigation of Clostridium butyricum on atopic dermatitis based on gut microbiota and TLR4/MyD88/ NF-κB signaling pathway

BACKGROUND

Probiotics, as common regulators of the gut microbiota, have been used in research to alleviate clinical symptoms of atopic dermatitis (AD).

OBJECTIVE

Our research team has previously identified a potential relieving effect of Clostridium butyricum on the treatment of AD, but the specific mechanism of how Clostridium butyricum alleviates AD has not yet been confirmed.

METHODS

In this study, we explored the relieving effect of Clostridium butyricum on AD through in vivo and in vitro experiments. AD mice induced by 2,4-dinitrofluorobenzene (DNFB) were orally administered with 1 × 108 CFU of Clostridium butyricum for three consecutive weeks.

RESULTS

Oral administration of Clostridium butyricum reduced ear swelling, alleviated back skin lesions, decreased mast cell and inflammatory cell infiltration, and regulated the levels of inflammation-related cytokines. Clostridium butyricum activated the intestinal immune system through the TLR4/MyD88/NF-κB signaling pathway, suppressed the expression of inflammatory factors IL-10 and IL-13, and protected the damaged intestinal mucosa.

CONCLUSION

Clostridium butyricum administration improved the diversity and abundance of the gut microbiota, enhanced the functionality of the immune system, and protected the epidermal barrier.

Key Taxa of the Gut Microbiome Associated with the Relationship Between Environmental Sensitivity and Inflammation-Related Biomarkers

Individual differences in environmental sensitivity are linked to stress-related psychiatric symptoms. In previous research, we found that high environmental sensitivity can be a risk factor for increased inflammation and gut permeability, particularly when gut microbiome diversity is low. However, the specific gut bacterial taxa involved in this interaction remain unclear. As a preliminary study, this research aimed to identify the key gut microbiome taxa associated with this relationship. Environmental sensitivity, gut microbiome composition, gut permeability (lipopolysaccharide-binding protein, LBP), and inflammation (C-reactive protein, CRP) biomarkers were evaluated in 88 participants. The interaction between environmental sensitivity and the relative abundance of the family Marinifilaceae (genus Butyricimonas) was a predictor of CRP levels. Similarly, the interaction between environmental sensitivity and relative abundance of the family Barnesiellaceae (genus Coprobacter), the family Akkermansiaceae (genus Akkermansia), the genus Family XIII AD3011 group, the genus GCA-900066225, or the genus Ruminiclostridium 1 predicted LBP levels. Individuals with high environmental sensitivity exhibited elevated CRP or LBP levels when the relative abundance of these taxa was low. Conversely, highly sensitive individuals had lower CRP or LBP levels when the relative abundance of these taxa was high. This study suggests that specific taxa serve as one of the protective factors against inflammation and gut permeability in individuals with high environmental sensitivity. Further in-depth studies are needed to confirm these associations and understand the underlying mechanisms.

Early changes in intestinal lymphoid and myeloid populations in experimental autoimmune encephalomyelitis

Intestinal immunity is associated with several autoimmune diseases, such as systemic lupus erythematosus, rheumatoid arthritis, and type 1 diabetes. Recent evidence also suggests its implication in the pathogenesis of autoimmune diseases affecting the central nervous system, such as multiple sclerosis (MS). However, there is ongoing debate regarding which part of the intestinal tract contributes to the development of MS. Therefore, our study aimed to explore the early changes in lymphoid and myeloid immune cells populations in experimental autoimmune encephalomyelitis (EAE), an animal model of MS. We also sought to determine the roles of the colon and/or small intestine in the pathogenesis of EAE. By using flow cytometry, we revealed a transient increase in T and B lymphocytes in the ileal lamina propria of EAE mice just before the onset of motor symptoms. Additionally, we highlighted an increase in dendritic cells and monocytes/macrophages in the colonic lamina propria of EAE animals during the presymptomatic phase. Altogether, our findings indicate that both small intestine and colon are involved in the pathogenesis of EAE, despite engaging distinct immunological processes. This study provides new insights for understanding the roles of intestinal lymphoid and myeloid immune cells on the pathogenesis of MS and other autoimmune diseases.

A spatiotemporal and machine-learning platform facilitates the manufacturing of hPSC-derived esophageal mucosa

Human pluripotent stem cell-derived tissue engineering offers great promise for designer cell-based personalized therapeutics, but harnessing such potential requires a deeper understanding of tissue-level interactions. We previously developed a cell replacement manufacturing method for ectoderm-derived skin epithelium. However, it remains challenging to manufacture the endoderm-derived esophageal epithelium despite possessing a similar stratified epithelial structure. Here, we employ single-cell and spatial technologies to generate a spatiotemporal multi-omics cell census for human esophageal development. We identify the cellular diversity, dynamics, and signal communications for the developing esophageal epithelium and stroma. Using Manatee, a machine-learning algorithm, we prioritize the combinations of candidate human developmental signals for in vitro derivation of esophageal basal cells. Functional validation of Manatee predictions leads to a clinically compatible system for manufacturing human esophageal mucosa.

Immune crosstalk between respiratory and intestinal mucosal tissues in respiratory infections

Mucosal tissues, including those in the respiratory and gastrointestinal tracts, are critical barrier surfaces for pathogen invasion. Infections at these sites not only trigger local immune response, but also recruit immune cells from other tissues. Emerging evidence in the mouse models and human samples indicates that the immune crosstalk between the lung and gut critically impacts and determines the course of respiratory disease. Here we summarize the current knowledge of the immune crosstalk between the respiratory and gastrointestinal tracts, and discuss how immune cells are recruited and migrate between these tissues during respiratory infections. We also discuss how commensal bacteria contribute to these processes.

Leveraging thiol-functionalized biomucoadhesive hybrid nanoliposome for local therapy of ulcerative colitis

Directly administering medication to inflamed intestinal sites for treating ulcerative colitis (UC), poses significant challenges like retention time, absorption variability, side effects, drug stability, and non-specific delivery. Recent advancements in therapy to treat colitis aim to improve local drug availability that is enema therapy at the site of inflammation, thereby reducing systemic adverse effects. Nevertheless, a key limitation lies in enemas' inability to sustain medication in the colon due to rapid peristaltic movement, diarrhea, and poor local adherence. Therefore, in this work, we have developed site-specific thiolated mucoadhesive anionic nanoliposomes to overcome the limitations of conventional enema therapy. The thiolated delivery system allows prolonged residence of the delivery system at the inflamed site in the colon, confirmed by the adhesion potential of thiolated nanoliposomes using in-vitro and in-vivo models. To further provide therapeutic efficacy thiolated nanoliposomes were loaded with gallic acid (GA), a natural compound known for its antibacterial, antioxidant, and potent anti-inflammatory properties. Consequently, Gallic Acid-loaded Thiolated 2,6 DALP DMPG (GATh@APDL) demonstrates the potential for targeted adhesion to the inflamed colon, facilitated by their small size 100 nm and anionic nature. Therapeutic studies indicate that this formulation offers protective effects by mitigating colonic inflammation, downregulating the expression of NF-κB, HIF-1α, and MMP-9, and demonstrating superior efficacy compared to the free GA enema. The encapsulated GA inhibits the NF-κB expression, leading to enhanced expression of MUC2 protein, thereby promoting mucosal healing in the colon. Furthermore, GATh@APDL effectively reduces neutrophil infiltration and regulates immune cell quantification in colonic lamina propria. Our findings suggest that GATh@APDL holds promise for alleviating UC and addressing the limitations of conventional enema therapy.

The renaissance of oral tolerance: merging tradition and new insights

Oral tolerance is the process by which feeding of soluble proteins induces antigen-specific systemic immune unresponsiveness. Oral tolerance is thought to have a central role in suppressing immune responses to 'harmless' food antigens, and its failure can lead to development of pathologies such as food allergies or coeliac disease. However, on the basis of long-standing experimental observations, the relevance of oral tolerance in human health has achieved new prominence recently following the discovery that oral administration of peanut proteins prevents the development of peanut allergy in at-risk human infants. In this Review, we summarize the new mechanistic insights into three key processes necessary for the induction of tolerance to oral antigens: antigen uptake and transport across the small intestinal epithelial barrier to the underlying immune cells; the processing, transport and presentation of fed antigen by different populations of antigen-presenting cells; and the development of immunosuppressive T cell populations that mediate antigen-specific tolerance. In addition, we consider how related but distinct processes maintain tolerance to bacterial antigens in the large intestine. Finally, we outline the molecular mechanisms and functional consequences of failure of oral tolerance and how these may be modulated to enhance clinical outcomes and prevent disease.

Type III interferons induce pyroptosis in gut epithelial cells and impair mucosal repair

Tissue damage and repair are hallmarks of inflammation. Despite a wealth of information on the mechanisms that govern tissue damage, mechanistic insight into how inflammation affects repair is lacking. Here, we investigated how interferons influence tissue repair after damage to the intestinal mucosa. We found that type III, not type I or type II, interferons delay epithelial cell regeneration by inducing the upregulation of Z-DNA-binding protein 1 (ZBP1). Z-nucleic acids formed following intestinal damage are sensed by ZBP1, leading to caspase-8 activation and the cleavage of gasdermin C (GSDMC). Cleaved GSDMC drives epithelial cell death by pyroptosis and delays repair of the large or small intestine after colitis or irradiation, respectively. The type III interferon/ZBP1/caspase-8/GSDMC axis is also active in patients with inflammatory bowel disease (IBD). Our findings highlight the capacity of type III interferons to delay gut repair, which has implications for IBD patients or individuals exposed to radiation therapies.

Importance of rectal over colon status in ulcerative colitis remission: the role of microinflammation and mucosal barrier dysfunction in relapse

BACKGROUND

Ulcerative colitis (UC) is a refractory inflammatory disease that affects the rectum and colon, with pivotal involvement of the rectal environment in relapse initiation. This study was conducted in two phases to examine the differences in gene expression between the rectum and colon and to identify relapse factors.

METHODS

In ***Study 1, RNA sequencing was performed on biopsies from the colon and rectum of patients with active UC, those with remission UC, and controls. In Study 2, the mucosal impedance (MI) values reflecting mucosal barrier function and the mRNA expression of tight junction proteins and inflammatory cytokines were examined in 32 patients with remission UC and 22 controls. Relapse was monitored prospectively.

RESULTS

In Study 1, comprehensive genetic analysis using RNA sequencing revealed distinct gene profiles in the rectum and sigmoid colon of patients with remission UC. The rectum of these patients exhibited an enriched immune response and apical junction phenotype with persistent upregulation of CLDN2 gene expression. In Study 2, even in patients with remission UC, the MI values in the rectum, but not in the sigmoid colon, were significantly decreased, whereas they were negatively correlated with CLDN2, IL-1β, and IL-6 expressions.

CONCLUSION

The status of the rectum in patients with remission UC differs from that of the colon, with microinflammation and impaired mucosal barrier function, which are associated with the upregulation of CLDN2, playing a role in relapse.

Biosignals in the Gut-Brain Axis Transmission: Function and Detection

The gut-brain axis (GBA) is an important information pathway connecting the brain, the central nervous system (CNS), and the gastrointestinal (GI) tract. On the one hand, gut microbiota can influence the function brain through GBA; on the other hand, the brain can also change the structural composition of gut microbiota via GBA. It contains a myriad of biosignals, such as monoamines, inflammatory cytokines, and macro-biomolecules, as the information carriers. Highly selective, sensitive, and reliable sensing techniques are essential to resolve the specific function of individual biosignals. This review summarizes the widely reported biosignals related to GBA and their functions, and organizes the latest sensing tools to provide feasible characterization ideas for GBA-related work. In addition, these low-cost, fast-responding sensors can also be used for early identification and diagnosis of GBA-related diseases (e.g., depression). Finally, the problems and deficiencies in this field are pointed out to provide a reference for the orientation of researchers in the sensing field.

Liquid-liquid separation in gut immunity

Gut immunity is essential for maintaining intestinal health. Recent studies have identified that intracellular liquid-liquid phase separation (LLPS) may play a significant role in regulating gut immunity, however, the underlying mechanisms remain unclear. LLPS refers to droplet condensates formed through intracellular molecular interactions, which are crucial for the formation of membraneless organelles and biomolecules. LLPS can contribute to the formation of tight junctions between intestinal epithelial cells and influence the colonization of probiotics in the intestine, thereby protecting the intestinal immune system by maintaining the integrity of the intestinal barrier and the stability of the microbiota. Additionally, LLPS can affect the microclusters on the plasma membrane of T cells, resulting in increased density and reduced mobility, which in turn influences T cell functionality. The occurrence of intracellular LLPS is intricately associated with the initiation and progression of gut immunity. This review introduces the mechanism of LLPS in gut immunity and analyzes future research directions and potential applications of this phenomenon.

Fungal microbiome in gut of systemic lupus erythematosus (SLE)-prone mice (pristane and FCGRIIb deficiency), a possible impact of fungi in lupus

The gut mycobiota (fungal microbiota) plays a crucial role in the immune system, potentially impacting autoimmune diseases such as systemic lupus erythematosus (SLE). Despite growing interest, data on intestinal fungi in SLE remain limited. This study thereby investigated the human-mimicked (mice) gut mycobiome and quantitative gut mycobiome analyses using universal fungal internal transcribed spacer 2 (ITS2) DNA next generation sequencing and real-time PCR, tracking time-series dynamics from preclinical to established SLE conditions in two SLE-prone mouse models. These models included pristane -induced mice, representing an environmental cause of SLE, and Fc gamma receptor RIIb (FcgRIIb) deficiency mice, representing a genetic factor. Fecal samples and different intestinal sections from mice aged 2-10 months were analyzed, including samples from 4-month-old and 11-month-old mice, which represented preclinical lupus (negative for anti-dsDNA) and established SLE conditions (positive for anti-dsDNA with proteinuria), respectively, alongside age-matched healthy controls. Results showed increased fungal diversity, specific changes in gut fungal species (i.e. increased Candida spp.), and an elevated Basidiomycota-to-Ascomycota (Basidiomycota/Ascomycota) ratio, which correlated with lupus activity in both lupus models. Linear discriminant analysis Effect Size (LEfSe; a possible representative organism) helped identify specific fungal difference between the lupus models. Our findings revealed that active lupus states may elevate gut fungal populations and alter fungal components in both the pristane and genetically susceptible SLE-prone mice, as indicated by mycobiota and quantitative mycobiota analyses. These changes could, in turn, influence disease activity. This research is essential for a deeper understand of the SLE-gut microbiome association, as the gut microbiome comprises both bacterial and fungal symbiosis. Manipulating fungal communities could present a potential therapeutic avenue for influencing disease outcomes in lupus. Further studies are crucial to clarify the direct role of gut fungi in lupus disease progression.

Effects supplementation of novel multi-enzyme on laying performance, egg quality, and intestinal health and digestive function of laying hens

This study investigated the effects of multi-enzyme supplementation on various aspects of laying hens, including laying performance, egg quality, intestinal health and digestive function. In total, 384 Jingfen No.6 laying hens at 65-week-age were randomly assigned to four distinct dietary treatments: a basal diet (CON), CON supplemented with 150 g/t multi-enzyme (T1), CON with 300 g/t multi-enzyme (T2), and 600 g/t multi-enzyme (T3). A significant linear (P = 0.044) and quadratic (P = 0.014) increase was observed in the laying rate, while the feed/egg ratio exhibited a linear (P = 0.001) and quadratic (P < 0.001) decrease with increasing multi-enzyme supplementation. Additionally, linear (P < 0.05) and quadratic (P < 0.05) increases were observed in yolk rate and haugh unit with increasing levels of multi-enzyme supplementation. The trypsin activity in the duodenum and crude protein digestibility showed linear (P < 0.05) and quadratic (P < 0.05) increase with the addition of multi-enzyme. Furthermore, lipase and amylase activities in the duodenum increased quadratically (P = 0.041) and linearly (P = 0.040), respectively. Both jejunal and ileal digesta viscosities showed linear (P < 0.05) and quadratic (P < 0.05) decrease with the increasing addition of multi-enzyme. Moreover, multi-enzyme supplementation significantly increased (P < 0.05) the number of goblet cells in the intestinal of the treatment groups. The mRNA expression of Occludin-1, mucin 2 (MUC-2), large neutral amino acids transporter small subunit 1 (LAT-1) in the jejunum were significantly increased (P < 0.05) in the treatment groups (T1, T2 and T3) compared to the CON group. Additionally, the mRNA expression of solute carrier family 6-member 19 (B0AT-1) and large neutral amino acids transporter small subunit 4 (LAT-4) were significantly evaluated (P < 0.05) in the T2 and T3 groups, respectively. In conclusion, multi-enzyme supplementation enhanced digestive enzyme activities and intestinal barrier function, reduced intestinal digesta viscosity, and regulated mRNA expression of intestinal amino acid and lipid transporter genes, thereby improving crude protein digestibility and positively affecting laying performance and egg quality in hens.

A gut microbial metabolite cocktail fights against obesity through modulating the gut microbiota and hepatic leptin signaling

BACKGROUND

Excessive body weight and obesity elevate the risk of chronic non-communicable diseases. The judicious application of the gut microbiome, encompassing both microorganisms and their derived compounds, holds considerable promise in the treatment of obesity.

RESULTS

In this study, we showed that a cocktail of gut microbiota-derived metabolites, comprising indole 3-propionic acid (IPA), sodium butyrate (SB) and valeric acid (VA), alleviated various symptoms of obesity in both male and female mice subjected to a high-fat diet (HFD). The 16S ribosomal RNA (rRNA) sequencing revealed that administering the cocktail via oral gavage retained the gut microbiota composition in obese mice. Fecal microbiota transplantation using cocktail-treated mice as donors mitigated the obesity phenotype of HFD-fed mice. Transcriptomic sequencing analysis showed that the cocktail preserved the gene expression profile of hepatic tissues in obese mice, especially up-regulated the expression level of leptin receptor. Gene delivery via in vivo fluid dynamics further validated that the anti-obesity efficacy of the cocktail was dependent on leptin signaling at least partly. The cocktail also inhibited the expression of appetite stimulators in hypothalamus. Together, the metabolite cocktail combated adiposity by retaining the gut microbiota configuration and activating the hepatic leptin signaling pathway.

CONCLUSIONS

Our findings provide a sophisticated regulatory network between the gut microbiome and host, and highlight a cocktail of gut microbiota-derived metabolites, including IPA, SB, and VA, might be a prospective intervention for anti-obesity in a preclinical setting. © 2024 Society of Chemical Industry.

Capsule robots for the monitoring, diagnosis, and treatment of intestinal diseases

Current evidence suggests that the intestine as the new frontier for human health directly impacts both our physical and mental health. Therefore, it is highly desirable to develop the intelligent tool for the enhanced diagnosis and treatment of intestinal diseases. During the past 20 years, capsule robots have opened new avenues for research and clinical applications, potentially revolutionizing human health monitor, disease diagnosis and treatment. In this review, we summarize the research progress of edible multifunctional capsule robots in intestinal diseases. To begin, we introduce the correlation between the intestinal microbiome, intestinal gas and human diseases. After that, we focus on the technical structure of edible multifunctional robots. Subsequently, the biomedical applications in the monitoring, diagnosis and treatment of intestinal diseases are discussed in detail. Last but not least, the main challenges of multifunctional capsule robots during the development process are summarized, followed by a vision for future development opportunities.

Identification of Key Genes in Fetal Gut Development at Single-Cell Level by Exploiting Machine Learning Techniques

The study of fetal gut development is critical due to its substantial influence on immediate neonatal and long-term adult health. Current research largely focuses on microbiome colonization, gut immunity, and barrier function, alongside the impact of external factors on these phenomena. Limited research has been dedicated to the categorization of developing fetal gut cells. Our study aimed to enhance our understanding of fetal gut development by employing advanced machine-learning techniques on single-cell sequencing data. This dataset consisted of 62,849 samples, each characterized by 33,694 distinct gene features. Four feature ranking algorithms were utilized to sort features according to their significance, resulting in four feature lists. Then, these lists were fed into an incremental feature selection method to extract essential genes, classification rules, and build efficient classifiers. Several important genes were recognized by multiple feature ranking algorithms, such as FGG, MDK, RBP1, RBP2, IGFBP7, and SPON2. These features were key in differentiating specific developing intestinal cells, including epithelial, immune, mesenchymal, and vasculature cells of the colon, duo jejunum, and ileum cells. The classification rules showed special gene expression patterns on some intestinal cell types and the efficient classifiers can be useful tools for identifying intestinal cells.

Functional insights of digestion, absorption, and immunity in different segments of the intestine in Hemibarbus labeo from transcriptomic analysis

The intestine is an important organ for food digestion and absorption and body immunity in fish. In this study, we investigated the abundance of transcripts from different segments of the intestinal tract using transcriptome sequencing technology in Hemibarbus labeo, to provide functional insights into digestion, absorption, and immunity in the anterior intestine (AI), middle intestine (MI), and posterior intestine (PI). We found 5646 differentially expressed genes (DEGs), which were significantly enriched to GO terms of carbohydrate metabolic process, transmembrane transport, iron ion binding, lipid metabolic process, and KEGG pathway of fat digestion and absorption, mineral absorption, protein digestion and absorption, vitamin digestion and absorption, indicating that the digestion and absorption function of food is different in AI, MI, and PI. In practice, most genes, enriched in the KEGG pathway for digestion and absorption of nutrients, are upregulated in AI and MI, indicating stronger roles for food digestion and absorption in these segments. Furthermore, we found that genes involved in the KEGG pathway of lysosome and endocytosis pathway are upregulated in PI, suggesting stronger antigen-presenting capabilities in PI. However, some cytokine receptor genes, including ccr4, cxcr2, tnfrsf9, il6r, csf3r, and cxcr4, are highly expressed in AI, reflecting the regional immune specialization in different segments. This study provides functional insights into digestion, absorption, and immunity in different segments of the intestine and supports the regional functional specialization within different segments of the intestine in H. labeo.

The role of enteric nervous system and GDNF in depression: Conversation between the brain and the gut

Depression is a debilitating mental disorder that causes a persistent feeling of sadness and loss of interest. Approximately 280 million individuals worldwide suffer from depression by 2023. Despite the heavy medical and social burden imposed by depression, pathophysiology remains incompletely understood. Emerging evidence indicates various bidirectional interplay enable communication between the gut and brain. These interplays provide a link between intestinal and central nervous system as well as feedback from cortical and sensory centers to enteric activities, which also influences physiology and behavior in depression. This review aims to overview the significant role of the enteric nervous system (ENS) in the pathophysiology of depression and gut-brain axis's contribution to depressive disorders. Additionally, we explore the alterations in enteric glia cells (EGCs) and glial cell line-derived neurotrophic factor (GDNF) in depression and their involvement in neuronal support, intestinal homeostasis maintains and immune response activation. Modulating ENS function, EGCs and GDNF level could serve as novel strategies for future antidepressant therapy.

Licorice-regulated gut-joint axis for alleviating collagen-induced rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is partially affected by the integrity of the intestinal barrier. Licorice (GC), a medicinal and food-related herb, exhibits potent anti-inflammatory activity; however, studies on its mechanisms of action in RA are limited.

METHOD

Using a bovine type-II collagen-induced arthritis rat model, this study examined how GC influences the gut-joint axis to decrease RA. The Th17/Treg cell ratios in the blood, colon, and joints were also measured. Metabolomics and 16S rRNA sequencing were applied to explore the effects of variations in gut flora and metabolites.

RESULTS

The arthropathological slices, inflammation markers, and joint inflammation index scores in the GC treatment group significantly differed from those in the CIA group. Studies on the effect of GC on the gut-joint axis showed changes in the levels of lipopolysaccharide and diamine oxidase, both directly associated with intestinal permeability. ZO-1, occludin, and claudin-1, three intestinal tight-junction proteins, may express themselves more when exposed to GC. By maintaining an appropriate Th17/Treg cell ratio in the blood, colon, and joints, GC may reduce impaired to the intestinal barrier. An imbalance in the intestinal microenvironment, caused by modifications in gut flora and endogenous substances, can damage the intestinal barrier. GC may modify the relative abundances of Papillibacter, Clostridium, Eubacterium, Helicobacter, Provotella, and Barnesiella during RA treatment by repairing the intestinal barrier. The metabolic differences were mainly related to primary bile acid biosynthesis, pyrimidine metabolism, steroid biosynthesis, biotin metabolism, and sphingolipid metabolism. A fecal microbiota transplantation experiment confirmed the involvement of the gut microbiota and its metabolites in GC-mediated RA therapy.

CONCLUSION

The results demonstrated that GC repairs the intestinal barrier and adjusts the gut-joint axis to manage immunological imbalance in RA.

LAMTOR1/mTORC1 promotes CD276 to induce immunosuppression via PI3K/Akt/MMP signaling pathway in Clostridium perfringens-induced necrotic enteritis of laying hens

Clostridium perfringens (C. perfringens) causes avian necrotic enteritis, leading to huge economic losses to the poultry industry. This pathogen induces host immunosuppression; however, the molecular mechanism is still unclear. Thus, we established a laying hen infection model to explore this mechanism. We randomly divided 20 one-old-day laying hens into the control and infection groups. The infection group was infected intragastrically with 1 × 109 colony-forming units of C. perfringens in 1 mL of sterile phosphate-buffered saline (PBS) once a day from d 17 to 20; the control group received the same volume of PBS without the bacterium. Twenty-four hours after the last challenge, we sacrificed the laying hens and collected the jejunum for analysis. The infection group presented alterations in blood biochemical parameters and necrotic lesion scores as well as damage to the jejunum. Proteomics revealed 427 upregulated and 291 downregulated proteins in the infection group. In the infection group, CD3, CD4, and CD8 messenger RNA expression (mRNA) expression was decreased; LAMTOR1 and mTORC1 mRNA expression was increased; CD276 protein expression was enhanced; and the PI3K/Akt/MMP pathway was activated in jejunum of laying hens. This is the first study to report CD276 expression in the jejunum related to immunosuppression in a laying hen model of necrotic enteritis. It provides some new key targets to potentially control avian necrotic enteritis.

Biological variability of human intraepithelial lymphocytes throughout the human gastrointestinal tract in health and coeliac disease

BACKGROUND

Intraepithelial lymphocytes are the first line of defence of the human intestinal immune system. Besides, their composition is altered on patients with coeliac disease (CD), so they are considered as biomarkers with utility on their diagnose and/or monitoring. Our aim is to address their variability through the human gastrointestinal tract in health and characterized them in further depth in the coeliac duodenum.

METHODS

Intraepithelial lymphocytes were isolated from human gastric, duodenal, ileal and colonic biopsies, then stained with specific antibodies and acquired by flow cytometry.

RESULTS

Our results confirmed that the profile of Intraepithelial lymphocytes change through the length of the human gastrointestinal tract. Besides and given the central role that Interleukin-15 (IL-15) elicits on CD pathogenesis; we also assessed the expression of its receptor revealing that there was virtually no functional IL-15 receptor on duodenal Intraepithelial lymphocytes. Nevertheless and contrary to our expectations, the active IL-15 receptor was not increased either on Intraepithelial lymphocytes from CD patients.

CONCLUSIONS

IL-15 might require additional stimulus to activate intraepithelial lymphocytes. These findings may provide novel tools to aid on a CD diagnosis and/or monitoring, at the time that provide the bases to perform functional studies in order of getting a deeper insight in the specific function that Intraepithelial lymphocytes elicit on CD pathogenesis.

The epithelial barrier theory and its associated diseases

The prevalence of many chronic noncommunicable diseases has been steadily rising over the past six decades. During this time, over 350,000 new chemical substances have been introduced to the lives of humans. In recent years, the epithelial barrier theory came to light explaining the growing prevalence and exacerbations of these diseases worldwide. It attributes their onset to a functionally impaired epithelial barrier triggered by the toxicity of the exposed substances, associated with microbial dysbiosis, immune system activation, and inflammation. Diseases encompassed by the epithelial barrier theory share common features such as an increased prevalence after the 1960s or 2000s that cannot (solely) be accounted for by the emergence of improved diagnostic methods. Other common traits include epithelial barrier defects, microbial dysbiosis with loss of commensals and colonization of opportunistic pathogens, and circulating inflammatory cells and cytokines. In addition, practically unrelated diseases that fulfill these criteria have started to emerge as multimorbidities during the last decades. Here, we provide a comprehensive overview of diseases encompassed by the epithelial barrier theory and discuss evidence and similarities for their epidemiology, genetic susceptibility, epithelial barrier dysfunction, microbial dysbiosis, and tissue inflammation.

Dynamic regulation of innate lymphoid cell development during ontogeny

The helper-like ILC contains various functional subsets, such as ILC1, ILC2, ILC3 and LTi cells, mediating the immune responses against viruses, parasites, and extracellular bacteria, respectively. Among them, LTi cells are also crucial for the formation of peripheral lymphoid tissues, such as lymph nodes. Our research, along with others', indicates a high proportion of LTi cells in the fetal ILC pool, which significantly decreases after birth. Conversely, the proportion of non-LTi ILCs increases postnatally, corresponding to the need for LTi cells to mediate lymphoid tissue formation during fetal stages and other ILC subsets to combat diverse pathogen infections postnatally. However, the regulatory mechanism for this transition remains unclear. In this study, we observed a preference for fetal ILC progenitors to differentiate into LTi cells, while postnatal bone marrow ILC progenitors preferentially differentiate into non-LTi ILCs. Particularly, this differentiation shift occurs within the first week after birth in mice. Further analysis revealed that adult ILC progenitors exhibit stronger activation of the Notch signaling pathway compared to fetal counterparts, accompanied by elevated Gata3 expression and decreased Rorc expression, leading to a transition from fetal LTi cell-dominant states to adult non-LTi ILC-dominant states. This study suggests that the body can regulate ILC development by modulating the activation level of the Notch signaling pathway, thereby acquiring different ILC subsets to accommodate the varying demands within the body at different developmental stages.

Recognizing the biological barriers and pathophysiological characteristics of the gastrointestinal tract for the design and application of nanotherapeutics

The gastrointestinal tract (GIT) is an important and complex system by which humans to digest food and absorb nutrients. The GIT is vulnerable to diseases, which may led to discomfort or even death in humans. Therapeutics for GIT disease treatment face multiple biological barriers, which significantly decrease the efficacy of therapeutics. Recognizing the biological barriers and pathophysiological characteristics of GIT may be helpful to design innovative therapeutics. Nanotherapeutics, which have special targeting and controlled therapeutic release profiles, have been widely used for the treatment of GIT diseases. Herein, we provide a comprehensive review of the biological barrier and pathophysiological characteristics of GIT, which may aid in the design of promising nanotherapeutics for GIT disease treatment. Furthermore, several typical diseases of the upper and lower digestive tracts, such as Helicobacter pylori infection and inflammatory bowel disease, were selected to investigate the application of nanotherapeutics for GIT disease treatment.

Dissecting Innate and Adaptive Immunity in Inflammatory Bowel Disease: Immune Compartmentalization, Microbiota Crosstalk, and Emerging Therapies

The intestinal immune system is the largest immune organ in the human body. Excessive immune response to intestinal cavity induced by harmful stimuli including pathogens, foreign substances and food antigens is an important cause of inflammatory diseases such as celiac disease and inflammatory bowel disease (IBD). Although great progress has been made in the treatment of IBD by some immune-related biotherapeutic products, yet a considerable proportion of IBD patients remain unresponsive or immune tolerant to immunotherapeutic strategy. Therefore, it is necessary to further understand the mechanism of immune cell populations involved in enteritis, including dendritic cells, macrophages and natural lymphocytes, in the steady-state immune tolerance of IBD, in order to find effective IBD therapy. In this review, we discussed the important role of innate and adaptive immunity in the development of IBD. And the relationship between intestinal immune system disorders and microflora crosstalk were also presented. We also focus on the new findings in the field of T cell immunity, which might identify novel cytokines, chemokines or anti-cytokine antibodies as new approaches for the treatment of IBD.

recAP administration ameliorates sepsis outcomes through modulation of gut and liver inflammation

Sepsis, broadly described as a systemic infection, is one of the leading causes of death and long-term disability worldwide. There are limited therapeutic options available that either improve survival and/or improve the quality of life in survivors. Ilofotase alfa, also known as recombinant alkaline phosphatase (recAP), has been associated with reduced mortality in a subset of patients with sepsis-associated acute kidney injury. However, whether recAP exhibits any therapeutic benefits in other organ systems beyond the kidney is less clear. The objective of this study was to evaluate the effects of recAP on survival, behavior, and intestinal inflammation in a mouse model of sepsis, cecal ligation and puncture (CLP). Following CLP, either recAP or saline vehicle was administered via daily intraperitoneal injections to determine its treatment efficacy from early through late sepsis. We found that administration of recAP suppressed indices of inflammation in the gut and liver but did not improve survival or behavioral outcomes. These results demonstrate that recAP's therapeutic efficacy in the gut and liver may provide a valuable treatment to improve long-term outcomes in sepsis survivors.

Intragastric administration of short chain fatty acids greatly reduces voluntary ethanol intake in rats

Alcohol use disorder (AUD) represents a public health crisis with few FDA-approved medications for its treatment. Growing evidence supports the key role of the bidirectional communication between the gut microbiota and the central nervous system (CNS) during the initiation and progression of alcohol use disorder. Among the different protective molecules that could mediate this communication, short chain fatty acids (SCFAs) have emerged as attractive candidates, since these gut microbiota-derived molecules have multi-target effects that could normalize several of the functional and structural parameters altered by chronic alcohol abuse. The present study, conducted in male alcohol-preferring UChB rats, shows that the initiation of voluntary ethanol intake was inhibited in 85% by the intragastric administration of a combination of SCFAs (acetate, propionate and butyrate) given before ethanol exposure, while SCFAs administration after two months of ethanol intake induced a 90% reduction in its consumption. These SCFAs therapeutic effects were associated with (1) a significant reduction of ethanol-induced intestinal inflammation and damage; (2) reduction of plasma lipopolysaccharide levels and hepatic inflammation; (3) reduction of ethanol-induced astrocyte and microglia activation; and (4) attenuation of the ethanol-induced gene expression changes within the nucleus accumbens. Finally, we determined that among the different SCFAs evaluated, butyrate was the most potent, reducing chronic ethanol intake in a dose-response manner. These findings support a key role of SCFAs, and especially butyrate, in regulating AUD, providing a simple, inexpensive, and safe approach as a preventive and intervention-based strategy to address this devastating disease.

Regionalization of intestinal microbiota and metabolites in the small intestine of the Bactrian camel

Introduction

Peyer's patches (PPs) are crucial antigen-inductive sites of intestinal mucosal immunity. Prior research indicated that, in contrast to other ruminants, PPs in the small intestine of Bactrian camels are found in the duodenum, jejunum, and ileum and display polymorphism. Using this information, we analyzed the microbial and metabolic characteristics in various segments of the Bactrian camel's small intestine to further elucidate how the immune system varies across different regions.

Methods

In this study, the microbiota and metabolite of 36 intestinal mucosal samples, including duodenal (D-PPs), jejunal (J-PPs), and ileal PPs (I-PPs), were profiled for six Bactrian camels using 16S rRNA gene sequencing and liquid chromatography with tandem mass spectrometry (LC-MS/MS). To confirm meaningful associations, we conducted connection analyses on the significantly different objects identified in each group's results. ELISA was used to analyze the levels of IgA, IgG, and IgM in the same tissues.

Results

The microbiota and metabolite profiles of J-PPs and I-PPs were found to be similar, whereas those of D-PPs were more distinct. In J-PPs and I-PPs, the dominant bacterial genera included Clostridium, Turicibacter, and Shigella. In contrast, D-PPs had a significant increase in the abundance of Prevotella, Fibrobacter, and Succinobacter. Regarding the metabolomics, D-PPs exhibited high levels of polypeptides, acetylcholine, and histamine. On the other hand, J-PPs and I-PPs were characterized by an enrichment of free amino acids, such as L-arginine, L-glutamic acid, and L-serine. These metabolic differences mainly involve amino acid production and metabolic processes. Furthermore, the distribution of intestinal immunoglobulins highlighted the specificity of D-PPs. Our results indicated that proinflammatory microbes and metabolites were significantly enriched in D-PPs. In contrast, J-PPs and I-PPs contained substances that more effectively enhance immune responses, as evidenced by the differential distribution of IgA, IgG, and IgM.

Discussion

The intestinal microenvironment of Bactrian camels displays distinct regional disparities, which we propose are associated with variations in immunological function throughout different segments of the small intestine. This study highlights the specific traits of the intestinal microbiota and metabolites in Bactrian camels, offering a valuable reference for understanding the relationship between regional intestinal immunity and the general health and disease of the host.

Complex immune network and regional consistency in the human gastric mucosa revealed by high-resolution spectral cytometry

The immune cellular landscape from the gastric mucosa remains largely unknown despite its relevance in several inflammatory conditions. Human gastric biopsies were obtained from the antrum, body and incisura from 10 individuals to obtain lamina propria mononuclear cells that were further characterized by spectral cytometry. Phenotypic hierarchical analyses identified a total of 52 different immune cell subsets within the human gastric mucosa revealing that T-cells (> 60%) and NK cells (> 20%) were the main populations. Within T-cells, CD4+ and CD8+ were equally represented with both subsets displaying mainly a memory and effector phenotype. NK cells, on the contrary, were largely of the early phenotype. No regional differences were observed for any subsets among the 3 locations. Following unsupervised analysis, a total of 82 clusters were found. Again, no differences were observed amongst locations although a great degree of inter-individual variability was found, largely influenced by the presence of H. pylori infection and dyspepsia. We have unraveled the human gastric immune cellular subset composition and a unique interindividual immune fingerprint with no inter-regional variations.

Sodium oligomannate disrupts the adherence of Ribhigh bacteria to gut epithelia to block SAA-triggered Th1 inflammation in 5XFAD transgenic mice

Sodium oligomannate (GV-971), an oligosaccharide drug approved in China for treating mild-to-moderate Alzheimer's disease (AD), was previously found to recondition the gut microbiota and limit altered peripheral Th1 immunity in AD transgenic mice. As a follow-up study, we here made advances by pinpointing a Lactobacillus murinus (L.m.) strain that highly expressed a gene encoding a putative adhesin containing Rib repeats (Ribhigh-L.m.) particularly enriched in 5XFAD transgenic mice. Mechanistically, Ribhigh-L.m. adherence to the gut epithelia upregulated fecal metabolites, among which lactate ranked as the top candidate. Excess lactate stimulated the epithelial production of serum amyloid A (SAA) in the gut via the GPR81-NFκB axis, contributing to peripheral Th1 activation. Moreover, GV-971 disrupted the adherence of Ribhigh-L.m. to gut epithelia via direct binding to Rib, which corrected the excess lactate, reduced SAA, and alleviated Th1-skewed inflammation. Together, we gained further insights into the molecular link between gut bacteria and AD progression and the mechanism of GV-971 in treating AD.

Recent advancements in targeting the immune system to treat hypertension

Hypertension is the key leading risk factor for death globally, affecting ∼1.3 billion adults, particularly in low- and middle-income countries. Most people living with hypertension have uncontrolled high blood pressure, increasing their likelihood of cardiovascular events. Significant issues preventing blood pressure control include lack of diagnosis, treatment, and response to existing therapy. For example, monotherapy and combination therapy are often unable to lower blood pressure to target levels. New therapies are urgently required to tackle this issue, particularly those that target the mechanisms behind hypertension instead of treating its symptoms. Acting via an increase in systemic and tissue-specific inflammation, the immune system is a critical contributor to blood pressure regulation and is considered an early mechanism leading to hypertension development. Here, we review the immune system's role in hypertension, evaluate clinical trials that target inflammation, and discuss knowledge gaps in pre-clinical and clinical data. We examine the effects of anti-inflammatory drugs colchicine and methotrexate on hypertension and evaluate the blockade of pro-inflammatory cytokines IL-1β and TNF-α on blood pressure in clinical trials. Lastly, we highlight how we can move forward to target specific components of the immune system to lower blood pressure. This includes targeting isolevuglandins, which accumulate in dendritic cells to promote T cell activation and cytokine production in salt-induced hypertension. We discuss the potential of the dietary fibre-derived metabolites short-chain fatty acids, which have anti-inflammatory and blood pressure-lowering effects via the gut microbiome. This would limit adverse events, leading to improved medication adherence and better blood pressure control.

Cellular Plasticity in Gut and Liver Regeneration

The intestine and liver share a unique regenerative property that sets them apart from other mammalian visceral organs. The intestinal epithelium exhibits rapid renewal, making it one of the fastest renewing tissues in humans. Under physiological conditions, intestinal stem cells within each intestinal crypt continuously differentiate into the different types of intestinal epithelial cells to maintain intestinal homeostasis. However, when exposed to tissue damage or stressful conditions such as inflammation, intestinal epithelial cells in the gastrointestinal tract exhibit plasticity, allowing fully differentiated cells to regain their stem cell properties. Likewise, hepatic epithelial cells possess a remarkable regenerative capacity to restore lost liver mass through proliferation-mediated liver regeneration. When the proliferation-mediated regenerative capacity is impaired, hepatocytes and biliary epithelial cells (BECs) can undergo plasticity-mediated regeneration and replenish each other. The transition of mammalian liver progenitor cells to hepatocytes/BECs can be observed under tightly controlled experimental conditions such as severe hepatocyte injury accompanied by the loss of regenerative capacity. In this review, we will discuss the mechanism by which cellular plasticity contributes to the regeneration process and the potential therapeutic implications of understanding and harnessing cellular plasticity in the gut and liver.

Retinoic acid and TGF-β orchestrate organ-specific programs of tissue residency

Tissue-resident memory T (TRM) cells are integral to tissue immunity, persisting in diverse anatomical sites where they adhere to a common transcriptional framework. How these cells integrate distinct local cues to adopt the common TRM cell fate remains poorly understood. Here, we show that whereas skin TRM cells strictly require transforming growth factor β (TGF-β) for tissue residency, those in other locations utilize the metabolite retinoic acid (RA) to drive an alternative differentiation pathway, directing a TGF-β-independent tissue residency program in the liver and synergizing with TGF-β to drive TRM cells in the small intestine. We found that RA was required for the long-term maintenance of intestinal TRM populations, in part by impeding their retrograde migration. Moreover, enhanced RA signaling modulated TRM cell phenotype and function, a phenomenon mirrored in mice with increased microbial diversity. Together, our findings reveal RA as a fundamental component of the host-environment interaction that directs immunosurveillance in tissues.